1. Field of the Invention
The present invention relates to a theft detection mechanism and an anti-theft device for a vehicle.
2. Description of Background Art
Anti-theft devices for a vehicle include 1) a device which has a sensor for sensing vibration, infrared rays, ultrasonic sound or the like or a circuit for detecting a break in a specific circuit near a steering wheel and sounds an alarm by the signal of the above described sensors or circuit when a theft is carried out, 2) an anti-theft alarm device for a motorcycle as described in Japanese Unexamined Utility Model Publication No. 57-27669 and 3) an alarm device for a motorcycle as described in Japanese Unexamined Patent Publication No. Hei 7-223508.
In the above described prior art 2), the anti-theft alarm device has an alarm circuit and an engine ignition circuit which are selectively turned on or off by a selector switch and sounds an alarm when the alarm circuit is selected by the selector switch and an alarm switch attached on a handle grip is turned on by gripping the handle grip.
In the above described prior art 3), the alarm device is set in a state in which an ignition switch is set at an alarm position and a key is taken out from the alarm position and the vehicle body is held using a stand. When the stand is moved to a stored position by a third person, an alarm sounding device is energized by a stand switch attached on the stand to sound an alarm.
The sensors of the anti-theft device of the prior art 1) described above have an inconvenience with regard to sounding an alarm, for example, when the vehicle body is touched and the vibration is mistaken for a theft of the vehicle even though the theft is not carried out or when and individual forgets to turn off a switch for activating the above described sensors. Moreover, the sensors described above have an inconvenience of having a complex, expensive mechanism.
The prior art 2) and 3) described above have a problem wherein a switch attached on a handle grip or a stand is activated to sound an alarm due to carelessness when the theft is not carried out.